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Abductor Pollicis Longus

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Abductor Pollicis Longus

Abductor Pollicis Longus

The structure indicated is the abductor pollicis longus muscle of the posterior forearm.

The abductor pollicis longus muscle is one of the muscles located in the deep layer of muscles in the posterior compartment of the forearm. There are 5 muscles in the deep layer of the posterior forearm:

  1. Supinator
  2. Abductor pollicis longus
  3. Extensor pollicis brevis
  4. Extensor pollicis longus
  5. Extensor indicis

The abductor pollicis longus muscle, as the name suggests abducts the thumb.

Origin: Posterior surface of proximal ulna, radius and interosseous membrane

Insertion: Base of 1st metacarpal

Innervation: Posterior interosseous nerve

Action: Abduction and extension of the thumb at carpometacarpal joint

Learn more about the muscles of the forearm in this tutorial.


Rectus Capitis Posterior Minor

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Rectus Capitis Posterior Minor

Rectus Capitis Posterior Minor
The structure indicated is the rectus capitis posterior minor muscle.

The rectus capitis posterior minor is one of 4 muscles which make up the suboccipital group of back muscles. This group of small muscles are located at the base of the occipital bone in the superior cervical region posteriorly. The four suboccipital muscles are:

  1. Rectus capitis posterior major
  2. Rectus capitis posterior minor
  3. Obliquus capitis inferior
  4. Obliquus capitis superior

Origin:  spinous process of atlas vertebrae CI

Insertion: occipital bone inferior to nuchal line

Innervation: posterior ramus of CI

Action: Extension of head

 

Learn more about the muscles of the back in this tutorial.

Levator Palpebrae Superioris

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Levator Palpebrae Superioris

levator palpebrae superioris

The structure indicated is the levator palpebrae superioris muscle.

The levator palpebrae superioris muscle is located in the upper eyelid and is responsible for raising the eyelid. Just like the rectus muscles, and oblique muscles of the eyeball, the levator palpebrae superioris muscle is innervated by the oculomotor nerve (cranial nerve III).

The eyelids themselves are supported by the tarsus – in the upper eyelid the superior tarsus, and in the lower eyelid, the inferior tarsus. These structures consist of dense connective tissue.

Origin: Roof of the orbit on sphenoid bone, above the optic foramen

Insertion: Anterior surface of superior tarsus and upper eyelid

Innervation: Oculomotor nerve (cranial nerve III)

Action: retraction and elevation of eyelid.

Axillary Vein

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Axillary Vein

Axillary Vein

The structure indicated is the axillary vein.

The axillary vein passes through the axilla, draining blood from the upper limb into the subclavian veins, which in turn drain blood to the brachiocephalic (innominate) veins, which unite to form the superior vena cava which then drains into the right atrium of the heart.

The axillary vein is formed from the brachial and the basilic veins, and begins at the inferior margin of the teres major and ends at the lateral border of the first rib, where it then becomes the subclavian vein.

Learn more about the veins of the body in this tutorial

Fibularis Longus

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Fibularis Longus

Fibularis Longus
Fibularis Longus

The structure indicated is the fibularis (peroneus) longus muscle of the leg.

The fibularis longus muscle is one of the muscles of the lateral compartment of the leg. The leg consists of three muscular compartments: anterior, posterior and lateral. The lateral compartment consists of two muscles:

  1. Fibularis (peroneus) longus
  2. Fibularis (peroneus) brevis

The lateral muscles are responsible for eversion of the foot and are innervated by the superficial fibular (peroneal) nerve, which is a branch of the common fibular nerve. The common fibular nerve is a branch of the sciatic nerve and divides into the superficial fibular nerve and the deep fibular nerve. The deep fibular nerve innervates the muscles of the anterior compartment of the leg.

The tendon of the peroneus longus passes underneath the foot to insert medially on the base of the first metatarsal and the distal medial cuneiform bone. In doing so, it runs along a groove in the cuboid bone and forms a sling for the foot, supporting the transverse arch.

Origin: superior lateral surface of fibula

Insertion: plantar surface of medial cuneiform bone and base of first metatarsal

Innervation: superficial fibular nerve

Action: eversion and plantarflexion of foot.

 

Learn more about the muscles of the leg in this tutorial.

Cephalic Vein

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Cephalic Vein

Cephalic vein

The structure indicated is the cephalic vein.

The cephalic and basilic veins are the main superficial veins of the upper limb. The cephalic vein originates from the dorsal venous network of the hand and drains into the axillary vein by passing through the deltoid and pectoralis major muscles.

In the cubital fossa, which is the area located anterior to the elbow joint, the cephalic vein is joined to the basilic vein via the median cubital vein.

In the clinical setting, the median cubital vein is a convenient and common location for obtaining venous access for the administration of fluids or intravenous medication.

Learn more about the veins of the body in this tutorial.

Leg – Arterial Supply

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Hi this is Peter from AnatomyZone and in this tutorial we’re going to take a look at the arterial supply to the leg. So this tutorial follows on from the one I did on the arterial supply to the knee.

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What we’re looking at here is a posterior view of the knee and the leg, and we can see the popliteal artery running behind the knee joint and it gives off two branches. You’ve got the posterior tibial artery, which you can see here in red. And if I rotate the model around slightly, you can see the anterior tibial artery in purple. So the posterior tibial artery gives off the peroneal, or fibular artery, which you can see here. Now the bit between the origin of the anterior tibial and the origin of the fibular artery, is sometimes referred to as the tibioperoneal trunk, or the tibioperoneal trunk. So this tibiofibular trunk gives off the fibular artery and the posterior tibial artery.

 

Now to begin with let’s take a look at the branches of the anterior tibial artery. So you can see it here in this model in purple, and it arises just below the inferior border of the popliteus muscle. And rotating the model around you can see how it enters into the anterior, or extensor compartment of the leg, just above the interosseus membrane. The branches of the anterior tibial artery include the posterior tibial recurrent, and the anterior tibial recurrent arteries proximally. The posterior tibial recurrent artery is not always present and its not shown on this model. The anterior tibial recurrent artery you can see here. I’ve just switched over to a different model, which illustrate how the anterior tibial recurrent artery anastomoses with the lateral inferior genicular branch of the popliteal. So if I rotate the model around you can see the lateral inferior genicular coming off the popliteal artery, and you can also see this other branch anastomosing, which is the circumflex fibular artery of the posterior tibial artery, which I’ll come back to talk about.

 

The anterior tibial artery runs down the length of the leg, along the interosseus membrane and then it gives off some distal branches as it approaches the ankle joint. It then terminates as the dorsalis pedis artery, which supplies the foot. So we’re looking at the ankle joint here and we can see some muscles of the extensor compartment. We’ve got the extensor digitorum longus muscle, the extensor hallucis longus muscles, and the tibialis anterior muscle.

 

So I’ve just zoomed in a little bit closer and you can see the distal branches, you’ve got the anterior medial malleolar artery and the anterior lateral malleolar artery. As well as the arteries I’ve just mentioned, there are also several muscular branches and perforating branches which come off the anterior tibial artery, to supply the muscles and the skin respectively.

 

Just looking from this anterior view of the ankle joint, you can see how the anterior tibial artery crosses the ankle joint, roughly midway between the medial and lateral malleoli.

 

Now coming back to the posterior tibial artery, let’s take a look at some of the branches. Proximally we’ve got the circumflex fibular artery which we looked at before. So this artery winds around the neck of the fibular and anastomoses with the lateral inferior genicular artery. The posterior tibial artery then descends posteriorly down the long and distally it gives off a few branches. There are some branches which come off to supply the medial malleolus, and then there’s also this branch which comes off called the communicating branch, which anastomoses with the communicating branch of the fibular artery, which you can see here. Coming even further distally, you can see another branch which comes off to supply the calcaneus, so there are also calcaneal branches.

 

The posterior tibial artery then terminates by dividing into the medial and lateral plantar arteries, to supply the plantar aspect of the foot. In addition to the branches I’ve just mentioned, there is also a nutrient artery of the tibia, which is given off by the posterior tibial, and there are also muscular and perforating branches.

 

Now returning proximally, the last artery to talk about is the fibular artery, or the peroneal artery. So the tibiofibular trunk divides into the posterior tibial and the fibular artery, or as some texts describe it, the posterior tibial artery gives off the fibular artery. So looking at the distal branches, the fibular artery, which you can see here gives off the communicating branch which anastomoses with the communicating branch of the posterior tibial, and then it also gives off this calcaneal branch and it also has branches which anastomose with the anterior tibial branches. So if I just rotate the model around anteriorly, you can see these branches which anastomose with the malleolar branches of the anterior tibial artery.

 

So that’s the arterial supply to the leg. Next we’ll look at the arterial supply to the foot.

Carotid Sinus

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Carotid Sinus

Carotid Sinus

The structure indicated is the carotid sinus.

The carotid sinus is located just above the bifurcation of the common carotid artery at the base of the internal carotid artery.

The carotid sinus is an important structure in regulating and maintaining blood pressure. It contains baroreceptors which are sensitive to increases in arterial blood pressure and subsequent increased pressure and stretching of the arterial walls. The carotid sinus receives innervation via cranial nerve IX (glossopharyngeal nerve). This nerve synapses in the nucleus tractus solitarii of the medulla oblongata which then indirectly adjusts the level of autonomic outflow and controls the body’s blood pressure by altering the cardiac output and smooth muscle tone in the vasculature.

Also located at the bifurcation of the common carotid artery are chemoreceptors which detect changes in the partial pressure of oxygen and carbon dioxide in the blood. This collection of chemoreceptors are known as the carotid body, and receives innervation via cranial nerves IX and X.


Abductor Hallucis

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Abductor Hallucis

Abductor Hallucis

The structure indicated is the abductor hallucis muscle of the foot.

The intrinsic muscles on the plantar aspect of the foot are divided into four layers. The abductor hallucis muscle is found in the first layer of muscles. There are three muscles in the first layer:

  1. Abductor hallucis
  2. Flexor digitorum brevis
  3. Abductor digiti minimi

The abductor hallucis muscle is located in the medial border of the foot and is responsible for the palpable bulk of muscle that you can feel on the inside of the foot. It inserts via a common tendon, together with the flexor hallucis brevis, onto the base of the proximal phalanx of the great toe.

Origin: Medial process of calcaneal tuberosity

Insertion: Medial plantar portion of proximal phalanx of great toe

Action: Abducts great toe at MTP joint and flexes great toe at MTP joint.

Innervation: Medial plantar nerve

 

Learn more about the muscles of the foot in this tutorial.

Medial Femoral Condyle

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Medial Femoral Condyle

Medial Femoral Condyle

The structure indicated is the medial condyle of the femur.

The distal end of the femur forms two rounded condyles which articulate with the tibia below and the patella anteriorly – the medial condyle and the lateral condyle.

The linea aspera is a roughened crest of bone on the posterior aspect of the femur. Distally the linea aspera forms two ridges known as the lateral supracondylar line and the medial supracondylar line which as the name suggests, terminate just superiorly to the lateral and medial femoral condyles respectively. At the end of the medial supracondylar line is a tubercle called the adductor tubercle.

In between the medial and lateral femoral condyles is the intercondylar fossa. On each condyle is a smaller epicondyle which serve as the point of attachment for the collateral ligaments – the medial collateral (MCL) and the lateral collateral ligaments (LCL).

Learn more about the femur in this anatomy tutorial.

Atrial Arteries

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Atrial Arteries

Atrial Arteries

The structures indicated are the atrial branches of the right coronary artery.

The atrial arteries come off the right coronary artery to supply the right atrium of the heart. The atrial arteries are often describes in terms of three groups:

  1. Anterior
  2. Lateral
  3. Posterior

The anterior and lateral branches mainly supply the right atrium, whereas the posterior branch supplies both the right and left atria.

Learn more about the blood supply to the heart in this anatomy tutorial.

Common Hepatic Artery

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Common Hepatic Artery

Common Hepatic Artery

The structure indicated is the common hepatic artery.

The common hepatic artery is one of three branches of the celiac trunk and is the first anterior branch that arises from the abdominal aorta. The abdominal aorta consists of anterior, posterior, and lateral branches. There are three anterior branches which supply the foregut, midgut and hindgut structures these are as follows:

  1. Celiac trunk – supplies foregut
  2. Superior mesenteric artery – supplies midgut
  3. Inferior mesenteric artery – supplies hindgut

The celiac trunk arises from the abdominal aorta at the level of the upper part of the first lumbar vertebra. It gives rises to three branches:

  1. Common hepatic artery
  2. Left gastric artery
  3. Splenic artery

The common hepatic artery divides into two branches: the hepatic artery proper and the gastroduodenal artery.

The hepatic artery proper divides into the right and left hepatic arteries.

The gastroduodenal artery terminates by dividing into the right gastro-omental artery (right gastro-epiploic) and the superior pancreaticoduodenal artery.

Learn all about the branches of the celiac trunk in this anatomy tutorial.

Foot Arteries

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Learn all about the anatomy of the arterial supply to the leg in this tutorial.

Hamate Bone

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Hamate Bone

Hamate Bone

The structure indicated is the hamate bone of the hand.

There are three groups of bones in the hand:

  1. Carpal bones (8 in total)
  2. Metacarpal bones
  3. Phalanges

The carpal bones are separated into two rows:

  1. Proximal row
  2. Distal row

The hamate bone is one of four bones in the distal row of carpals (hamate, capitate, trapezium, trapezoid). It is named after its small hook-like process (“hamulus” comes from the Latin meaning hook). Several structures attach to the hook of the hamate bone. The hamate bone has the following articulations:

  • Radial: capitate
  • Ulnar: pisiform
  • Proximal: lunate
  • Distal: metacarpals of 4th and 5th

Learn more about the bones of the hand in this anatomy tutorial.

Extensor Carpi Ulnaris

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Extensor Carpi Ulnaris

Extensor Carpi Ulnaris

The structure indicated is the extensor carpi ulnaris muscle of the forearm.

The extensor carpi ulnaris muscle is one of 7 muscles located in the superficial compartment of the posterior forearm. The posterior forearm consists of a superficial and a deep compartment. The superficial compartment contains 7 muscles, whereas the deep compartment contains 5 muscles.

The superficial compartment of the posterior forearm includes the following 7 muscles:

  1. Brachioradialis
  2. Extensor carpi radialis longus
  3. Extensor carpi radialis brevis
  4. Extensor digitorum
  5. Extensor digiti minimi
  6. Extensor carpi ulnaris
  7. Anconeus

The muscles of the posterior compartment of the forearm originate from the lateral epicondyle of the humerus and the supraepicondylar ridge and they are all innervated by the radial nerve.

Origin: lateral epicondyle of humerus and posterior border of ulna

Insertion: base of 5th metatarsal

Action: extension and abduction of wrist

Innervation: Posterior interosseous nerve

 

Learn more about the anatomy of the forearm muscles in this tutorial.


Splenic Artery

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Splenic Artery

Splenic Artery

The structure indicated is the splenic artery.

The splenic artery is one of three branches of the celiac trunk, which is the first anterior branch that arises from the abdominal aorta. The abdominal aorta consists of anterior, posterior, and lateral branches. There are three anterior branches which supply the foregut, midgut and hindgut structures these are as follows:

  1. Celiac trunk – supplies foregut
  2. Superior mesenteric artery – supplies midgut
  3. Inferior mesenteric artery – supplies hindgut

The celiac trunk arises from the abdominal aorta at the level of the upper part of the first lumbar vertebra. It gives rises to three branches:

  1. Common hepatic artery
  2. Left gastric artery
  3. Splenic artery

The splenic artery supplies blood to the spleen, the pancreas and has branches which supply the stomach. The splenic artery gives rise to the following branches:

  • Pancreatic branches
  • Short gastric arteries
  • Left gastro-omental (left gastroepiploic) artery
  • Posterior gastric arteries

Learn all about the branches of the celiac trunk in this anatomy tutorial.

Flexor Digiti Minimi Brevis

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Flexor Digiti Minimi Brevis

Flexor Digiti Minimi Brevis

The structure indicated is the flexor digiti minimi brevis muscle of the foot.

The intrinsic muscles on the plantar aspect of the foot are divided into four layers. The flexor digiti minimi brevis muscle is located in the third layer of intrinsic foot muscles. There are three muscles located in this layer:

  1. Flexor hallucis brevis
  2. Adductor hallucis
  3. Flexor digiti minimi brevis

Origin: Base of 5th metatarsal

Insertion: lateral base of proximal phalanx of little toe

Action: flexes little toe at metatarsophalangeal joint

Innervation: lateral plantar nerve

 

Learn more about the anatomy of the foot muscles in this tutorial.

Anterior Inferior Iliac Spine

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Anterior Inferior Iliac Spine

Anterior Inferior Iliac Spine

The structure indicated is the anterior inferior iliac spine of the pelvic bone.

The pelvic bones consist of three parts:

  1. Ilium
  2. Ischium
  3. Pubis

The anterior part of the ilium consists of two bony spines. Superiorly is the anterior superior iliac spine (ASIS), and inferiorly is the anterior inferior iliac spine. Posteriorly is the posterior superior iliac spine and the posterior inferior iliac spine.

The rectus femoris muscle of the quadriceps group of thigh muscles attaches to the anterior inferior iliac spine, as well as the iliofemoral ligament.

Learn more about the anatomy of the pelvic bones in this anatomy tutorial.

Vertebral Artery

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Vertebral Artery

Vertebral Artery

The structure indicated is the vertebral artery.

The vertebral arteries arise from the first part of the subclavian artery. Two other arteries are given off from the first part of the subclavian artery – the internal thoracic artery and the thyrocervical trunk. The vertebral and internal carotid arteries provide the arterial supply to the brain, forming the Circle of Willis at the base of the brain.

After the vertebral artery is given off from the subclavian artery, it passes through the transverse foramina of cervical vertebrae C1 to C6. It then enters the skull via the foramen magnum.

The vertebral arteries unite to form the basilar artery. Before forming the basilar artery, the vertebral arteries give off three branches. Two of these branches unite with their contralateral branches to form the anterior spinal artery and the posterior spinal artery. The third branch of the vertebral artery is the posterior inferior cerebellar artery.

The anterior spinal artery runs down the spinal cord in the anterior median fissure. The posterior spinal artery runs down the posterior surface of the spinal cord.

Learn more about the blood supply to the spinal cord in this tutorial.

Posterior Inferior Iliac Spine

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Posterior Inferior Iliac Spine

Posterior Inferior Iliac Spine

The structure indicated is the posterior inferior iliac spine of the pelvic bone.

The pelvic bone consists of three parts:

  1. Ilium
  2. Ischium
  3. Pubis

The posterior part of the ilium consists of two bony spines. Superiorly is the posterior superior iliac spine, and inferiorly is the posterior inferior iliac spine. Anteriorly is the anterior superior iliac spine and the anterior inferior iliac spine.

Learn more about the anatomy of the pelvic bones in this tutorial.

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